Tuesday, March 25, 2014

Setting up a CAN-BUS Interface for a Jeep JK, with pin out information.

Some information you should know.
The standard OBDII port inside a Jeep Wrangler, does not allow you to communicate directly to the comfort/Interior CAN-BUS.

You need to physically bypass it, by tapping directly into the Interior CAN-BUS.
There are quite a few places where you can do this, the easiest and safest place to get to the CAN-BUS is to connect two wires directly to the CAN-BUS pins on the radio connector.

Why you should not use the ELM327 for this purpose.
Just to set things right, firstly there is nothing wrong with the ELM327 is just does not suite this purpose.

Not going into too much detail with the ELM327 OBD2 Scanner.
You can  use the ELM327 and connect wires from Pin 6 and Pin 14 on the ELM327 OBD2 Connector to the CAN-BUS White/Orange (CAN Low Negative) and White/Grey (CAN H Positive) on the Radio connector.
Problem is the ELM327 has a small buffer and also there are 1000s of Fake ELM327 devices out there and their performance resaults arn't always good and will most probably give a [Buffer Full] error message after a few 100 CAN-BUS broadcasted messages.

CAN-BUS Shield for Arduino UNO
In this I'm making use of SeeedStudio's version,

A better tool  to use would be something faster that can handle the CAN-BUS traffic such as a circuit board that makes use of the MCP2515 chip created by a company called Microchip.

In this example we are making use of the CAN-BUS Shield which snaps onto an Arduino UNO.
You also get a similair board that will work with the Pi.

The Seup is pretty simple (See below illustration)

If you have a Male to Female USB Extender cable you can cus it in half, then join one end to the radio, then run it into the Jeep's glove box.

The other end you can connect to to the CAN-BUS Shield, So then when ever you need to experiment, you can simply just make the USB Connection.

For the next blog post i will create an Arduino sketch that  will monitor all data on the CAN-BUS and out put it to the Serial Bus of the Arduino, then we can putty into the Arduino and dump all of the data to a file , which we can then analyse using excel or SQL database queries.

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